An unnamed close friend of the singer has said the inquiry has foundered because detectives have been unable to find evidence to substantiate the claims, the Sunday Times reported. The paper added Richard was understood to have provided police with evidence that he was never alone with two men who allege that he assaulted them in separate incidents in the 1980s.

“Cliff has given police evidence that he was never on his own on the days when the alleged attacks took place,” the friend was quoted as saying.

South Yorkshire police said the force “won’t be providing a running commentary on the investigation. The inquiry continues and inquiries are ongoing”.

There was no comment from the singer, who has not been arrested or charged, and who is preparing for a UK concert tour to mark his 75th birthday, performing in Birmingham, Liverpool, Manchester, Glasgow, Newcastle, Nottingham and culminating in a five-night run at the Royal Albert Hall in London.

Richard was in Portugal in August last year when the BBC broadcast live footage of a police raid on his £2.5m home in Sunningdale, Berkshire. The raid happened without his knowledge and South Yorkshire police were later criticised when an inquiry found they had caused unnecessary distress to the singer, who “should not have been informed of the allegations through the media”. Richard later sold the property.